Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1617814

Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU mask

Show all headers | View raw

On Wed, Apr 05, 2017 at 09:39:43AM +0200, Ingo Molnar wrote:

> > While converting the existing users I tried to stick with the rules
> > above however… well mostly CPUFREQ tries to temporary switch the CPU
> > mask to do something on a certain CPU and then switches the mask back it
> > its original value. So in theory `cpus_ptr' could or should be used.
> > However if this is invoked in a migration disabled region (which is not
> > the case because it would require something like preempt_disable() and
> > set_cpus_allowed_ptr() might sleep so it can't be) then the "restore"
> > part would restore the wrong mask. So it only looks strange and I go for
> > the pointer…
> 
> So maybe we could add the following facility:
> 
> 	ptr = sched_migrate_to_cpu_save(cpu);
> 
> 	...
> 
> 	sched_migrate_to_cpu_restore(ptr);
> 
> ... and use it in the cpufreq code. Then -rt could simply define migrate_disable() 
> to be:

Argh, no....

We have plenty of proper per-cpu kthreads / workqueue and other APIs to
do this.

Not to mention that implementing the above in a non-broken way has user
visible side-effects, which ugly.

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[RFC PATCH] kernel: sched: Provide a pointer to the valid CPU mask Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2017-04-04 20:50 +0200
  Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Ingo Molnar <mingo@kernel.org> - 2017-04-05 09:40 +0200
    Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2017-04-05 10:40 +0200
      Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Ingo Molnar <mingo@kernel.org> - 2017-04-06 08:20 +0200
        Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2017-04-06 09:40 +0200
          Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Ingo Molnar <mingo@kernel.org> - 2017-04-06 10:10 +0200
            Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2017-04-06 11:30 +0200
              Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Peter Zijlstra <peterz@infradead.org> - 2017-04-06 11:50 +0200
                Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Thomas Gleixner <tglx@linutronix.de> - 2017-04-06 13:00 +0200
                Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Peter Zijlstra <peterz@infradead.org> - 2017-04-06 13:50 +0200
            Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Peter Zijlstra <peterz@infradead.org> - 2017-04-06 11:40 +0200
              Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Peter Zijlstra <peterz@infradead.org> - 2017-04-06 11:50 +0200
            Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Thomas Gleixner <tglx@linutronix.de> - 2017-04-06 12:40 +0200
              Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Ingo Molnar <mingo@kernel.org> - 2017-04-06 13:10 +0200
                Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Thomas Gleixner <tglx@linutronix.de> - 2017-04-06 13:20 +0200
                Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Ingo Molnar <mingo@kernel.org> - 2017-04-07 09:20 +0200
    Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Peter Zijlstra <peterz@infradead.org> - 2017-04-06 11:40 +0200
  Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Peter Zijlstra <peterz@infradead.org> - 2017-04-06 11:40 +0200
    Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2017-04-06 11:50 +0200
      Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Peter Zijlstra <peterz@infradead.org> - 2017-04-06 12:40 +0200
        Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Thomas Gleixner <tglx@linutronix.de> - 2017-04-06 12:50 +0200
          Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Peter Zijlstra <peterz@infradead.org> - 2017-04-06 13:00 +0200
            Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Thomas Gleixner <tglx@linutronix.de> - 2017-04-06 13:10 +0200
              Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Peter Zijlstra <peterz@infradead.org> - 2017-04-06 14:00 +0200
                Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Thomas Gleixner <tglx@linutronix.de> - 2017-04-06 14:00 +0200
                Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU  mask Peter Zijlstra <peterz@infradead.org> - 2017-04-06 14:40 +0200

csiph-web